HOWTO: Move the Minimize/Maximize/Close Buttons back the Right SideHit ALT - F2
Type gconf-editor
Go to the following:apps --> metacity --> general
Find the button_layout parameter, right mouse click, and select Edit Key
Change the value to the following:menu:minimize,maximize,close
Don't forget the colon on the left side of the text. "menu" is not necessary.

To change scree resolution from Command prompt:
$ xrandr -s 1024*768

How to change MAC address of NIC card in Ubuntu:
Type following command either in /etc/rc.local file or at command prompt:

Public key error while trying to run update command$ sudo apt-get updategives following error :W: GPG error: http://ppa.launchpad.net lucid Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D2B5F4E7C3BB95BB

What to do if ubuntu hangs? Or how to restart Xserver:
press : Ctrl + Alt + Backspace
or press: Alt + Backspace
This usually restarts xserver. You need to login again to the system.

Using Bash History Effectively:
Type the following command to get a list of all related commands with their history numbers:$ history | grep -i "search string"
Once you've found the command you want, you can execute it specifically by its number$ !<history_command_number>

How to prevent Auto Locking the computer Screen:
1. Open file "/etc/default/acpi-support" and comment following line:

# Comment this out to disable screen locking on resume LOCK_SCREEN=true

2. Use following command to combine multiple files into single PDF file. The output file name is "singleCombinedPdfFile.pdf". The input file names are all files in the current directory, bcoz we used "*.pdf".

How to find out the maximum RAM capacity and the number of RAM slots available in the Computer?$sudo dmidecode -t 16
To see complete memory information, including the info displayed by above command along with currently installed memory information (RAM speed, size, etc.), use:
$ sudo dmidecode -t memory